Wax compositions



United States Patent WAX COMPOSITIONS Wildon T. Harvey, Ho-ckessin, Del., and Seymour W. Ferris, Mount'Holly, N.J., assignors to Sun Oil Comparry, Philadelphia, Pa., a corporation of New Jersey No Drawing. Application February 4, 1958 Serial No. 713,089

4 Claims. ct. 229-31 unsightly appearance, in obtaining poor coverage with subsequent softening when filled with liquids, in blocking at relatively low temperatures, in easily, fracturing on being subjected to an impact, and in requiring conditions during application to paper containers which cannot be met with existing equipment, such as relatively high temperatures. For example, United States Patent Number 2,624,501 describes and claims aparafiinwax which is especially suitable for coating fibrous sheet materials and containers such as milk containers. However, actual commercial use has disclosed several disadvantages of coatings formed from this wax. Such coatings on fibrous sheet materials may develop minute imperfections which impart a serpentine efiect to the coating thereby creating an unsightly appearance and leakage of packaged'liquid materials through the imperfections may develop. A further difiiculty of this Wax, as has been found, is the tendency of coatings formed. therefrom to fracture on sufiering' an impact so that leaks develop through the fracture.

An object of the present invention is to provide a wax composition especially suitable for coating fibrous containers for fluids. A particular object is to provide a wax composition effective for coating paper containers for liquids which imparts a pleasing appearance to the resulting article of manufacture, while obtaining good coverage and good blocking characteristics, and which can be readily applied with existing equipment. A further object is to provide a process for the preparation of such wax compositions. A specific object'is to provide a wax composition which, when formed as a coating for a fibrous container, will not easily fracture on suffering an impact. 7

It has now been found that by blending two paraffin waxes having specific properties in specific proportions, a wax composition achieving the above and other objects is obtained.

As used herein, melting points are determined by ASTM 1387-42, penetrations by ASTM 135-52 and viscosities (SUS- Saybolt Universal Seconds) by ASTM D446-53, unless otherwise stated. Modulus of rupture, which is a measure of the tendency of the wax to fracture on suffering an impact, which may bein the form of a sharp impact or a continuous pressure, is determined by forming a wax into strips of specified dimensions (0.15 inch thick by 0.5 inch wide by 3 inches long) by solidifying molten wax on the surface of water to form the de ice 2 sired thickness, and cutting to the other dimensions; Each strip is placed upon two horizontal supports two inches apart and is broken by incremental weighting at the center, the test being made at a temperature of 73 F. The breaking weight in p.s.i. (pounds per square inch) of cross sectional area is the modulus of rupture.

The first paraffin wax must have a melting point of from 125 F. to 130 F., a penetration (at 77 F.) of from 17 to 23 (about 100 atlOil" R), a viscosity (at 210 F.) of from 36 to 39 SUS and a modulusof rupture (at'73 F.) f about 270' r 340. A para'ffin' meeting these specifications may be prepared by two methods: In the first method of preparing the described ar'afiin wax,a slack wax from the dewaxing of lubricating oil, which may contain about oil, is vacuum distilled and the fraction distilling between about 390 and 565 F. at 2 mm. of mercury pressure is collected This fraction-is dissolved in a solvent, preferably a mixture of methyl ethyl ketone and benzene'in' about equal volumes. Dissolution is performed at an elevated temperature, from about 165 F. to 195 beingsuitable,and advantageou'sly about 6 parts by volume of solvent perpart of wax is used. The solution is slowly cooled to a temperatu're' of from 75 f F. to 83 F. and the waxwhich precipitates at this temperature. is se arated. such as by filtration. The" solution separated from the precipitated wax further slowly cooled t'o a temperature of from 28 F. to 33 F. and thewaxwhich precipitates at this temperature is separated and forms the. first paraffinic W'ax of the present compositions. v Preferably the wax after separation from solution is washed such. as with the solvent employed for dissolution, preferably at the same temperature as used for filtration, na'rnelyfrom 28 F to 32"FI, and the wax is then separated. H

An alternate method of preparin the first paratlin wax of the present invention which provides considerable flexibility in obtaining the desired waxproduct is-to sepa'rate from slack wax two distillate fractions, one dis.- tilling in the range of fromab'out 390 F. to 47-5 F. at 2 mm. of mercury pressure and a second fraction distilling in the range of from about 450 F. to 565 F. at 2 mm. of mercury pressure. As usually occurs, the initial boiling. point of the second fraction will overlap the endpoint of the first-mentioned distilled fraction. .The lower boiling distillate fraction is dissolved ina solvent as above de scribed and the solution cooled to a temperature of from 25 F. to 31 F. The wax which precipitates at this temperature is separated as by filtering. The higher boiling distillate fraction is dissolved in a solvent as above described, except that a lower proportion of solvent to wax, say about 4.5 parts of solvent per part of is advantageously used, and the solutionslowly cooled toa temperature of from 72 F. to 82 F. The wax which precipitates at this temperature is separatedsuch as by filtering and the remaining. solution is further slowly. cooled to a temperature of from..25 F. to- 31 F. -The wax which precipitates at this latter temperature is separated as by filtering. The two distillate waxes so-prepared:

are combined to form the first paraffin wax of the present invention. Considerable flexibility is. obtained since the blending may be in various proportions so that the properties of the resulting .wax mixture is within the limits abovedescrib'ed for the first paraffin wax; If desired,.the two wax'es can' be washed and dried prior to blending, or the wetwaxes may be combined and simultaneously washed and thenrecovered by removal ofthe wash liquid. In. general, from about 69% to by weight of the. paraffin wax will consist ofwax from the lower boiling, distillate fraction since, as has been found, such mixture gives a wax having properties within those defined for the first paraffin wax of the invention.

The second pa'raflin wax of theinvent'ion must'ha've' a,

3 melting point of from about 148 F. to 154 F., a penetration (at 100 F.) of from 13 to 19, a viscosity (at 210 F.) of from 40 to 46 SUS and a modulus of rupture of from about 340 to 400.

. The second parafiin wax of the subject wax composition is preferably prepared from a slack wax from the dewaxing of lubricating oil or from topping a high wax content crude oil, distilling the reduced wax crude under vacuum, and collecting the fraction distilling in the range of from about 450 F. to 565 F. at 2 mm. of mercury pressure. The distillate fraction is dissolved in a solvent which is preferably a mixture of methyl ethyl ketone and benzene in about equal parts by volume, dissolution advanta ously being at a temperature of from about 165 F. to 190 F. as above described. using about 2 parts of solvent per part of wax. The so ution is sl wly cooled to a temperature of from about 77 F. to 83 F. and t e wax precipitated at this temperature is separated and t e se arated wax is washed such as with the solvent emplo ed for disso ution. preferably at the same temp rature as used for filtrat on. and the wax recovered. This wax forms the second paraffinic wax of the present invention.

In preparing the wax constituents of t e subiect paraffin wax composition. the described operating variables must be observed in order to secure the advanta es of t e invention. However, the solvent used for dissolution of the wax fractions can be varied somewhat and good results obtained. The described solvent. cons sting of about equal parts by volume of methyl ethyl ketone and benzene gives good results. but more or less of the two const tuents. say rom 30% to 70% by volume of ben ene can be used. Also. ot er so vents can replace. at least in part. eit er t e meth l et yl ket ne or benzene. For example. toluene can be subs ituted for a portion of the ben ene. and good results obtained.

The two parafiin Waxes which form t e wax composition of the present invention must be blended in specific pro ortions in order to obtain t e advantages of the present n ention. The first described paraflin wax forms from 70% to 85% of the composit on. and the sec nd pa affin is present in a quant ty of from 30% to 15%. This blend. as shown here nafter by example. has novel and unobvious properties including a remarkably high modulus of rupture. w ich is at least 420. and may be as high as 500. and is alwa s at least 30 units higher than the modulus of rupture of eit er of the wax components of the mposit on. The blend has a meltin point of from 130 F. to 132 F., a viscosity (at 210 F.) of from 38 to 1 SUS, and a penetration (at 100 F.) of from 50 to 80.

In order to demonstrate a specific embodiment of the esent invention and the advantages thereof. two paraffin waxes were re ared as f llows: slack wax fr m the dewaxin of lubricating oil and contain ng about 30% oil was distilled at a ressure of 2 mm. of mercury. A distillate fract on boilin in the range of from about 390 F. to 475 F. and another d stillate fraction boil ng in the range f from a o t 45 F. to 565 F. were collected. T e ower b iling fraction was dissolved in a mixture of 60% methyl ethyl ketone and 40% benzene at an elevated temperature of about 170 F.. about 6 parts of the solvent er part of wax being used. T e solution was slowly cooled to 28 F. and the p ecipitated wax was filtered. was ed and dr ed. T e h gher boiling distillate fraction was dissolved in a s milar solvent as above described. usin about 4.5 arts of solvent ner part of wax, and t e resulting solution co led to 80 F. The wax precipitated was se arated by filtering and the filtrate was further cooled to 30 F. The wax separating at this latter temperature was separated by filtering and was washed and dried. The two so-formed waxes were blended in quantities such that the final composition contained 72% of wax from the lower boiling distillate and 28% from the higher boiling distillate. The resulting wax product had a melting point of 127 F., a viscosity (at 210 F.) of 39.0, a penetration (at 77 F.) of and a modulus of rupture (at 73 F.) of about 338.

The second paraffin wax component of the present composition was prepared by topping a high wax content crude petroleum to about 38% bottoms. The bottoms were charged to a vacuum distillation operation operating at 2 mm. of mercury pressure, and the fraction distilling between 450 and 565 F. was collected. This fraction was dissolved in a solvent consisting of a mixture of about 60% methyl ethyl ketone and about 40% benzene at a temperature of about 180 F., about 2 parts of solvent per part of wax being used. The resulting solution was slowly cooled to 80 F. and the wax precipitated at this temperature was separated, washed and dried. This second parafiin wax had a melting point of 151 F., a viscosity (at 210 F.) of 43.6, a penetration (at 77 F.) of

. 12 and a modulus of rupture (at 73 F.) of 352.

Modulus of rupture, p.s.l. of cross sectional area 2nd wax, weight percent 1st wax, weight percent Milk containers formed from cardboard were coated with the wax composition in a commercial operation using existing equipment. No difliculties such as fouling of the equipment with solidified or partially solidified wax were observed. The coated container exhibited a high gloss with no serpentine effects. Good coverage is obtained and no fracturing is observed on subjecting the coated containers to impacts designed to be more severe than impacts received in service, and blocking of the containers when stored in contact with each other at temperatures as high as F. is not observed. Also, blocking of slabs formed from the subject wax composition and stored in contact with each other is not observed at temperatures of about 100 F.

It does not appear that other waxes can be substituted for either component of the present composition without changing one or more properties of the resulting compositions so that the objects of the present invention are defeated. For example, a parafiin wax having a melting point of 142 F., a viscosity of 40 (SUS at 2l0 F.) a penetration (at 77 F.) of 12 and a modulus of rupture of 324 when substituted for the higher melting paraffin wax of the present composition gave a blend in which the modulus of rupture showed no synergism. The substitution of still other waxes having closely related properties but lying outside of those defined for the two components of the present compositions were made, none of which were operative in providing all of the advantages of the present compositions.

The invention claimed is:

1.- A wax composition consisting essentially of from 70% to 85% of a paraffin wax having a melting point of from F. to 132 F., a penetration at 77 F. of from 17 to 23, a viscosity at 210 F. of from 36 to 39 SUS and a modulusof rupture at 73 F. of from about 270 to 340, and from to of a paraflin wax having a melting point of from 148 F. to 154 F., a penetration at 100 F. of from 13 to 19, a viscosity at 210 F. of from to 46 SUS, and a modulus of rupture of from about 340 to 400.

2. A wax composition according to claim 1 wherein the modulus of rupture is at least 30 units higher than the modulus of rupture of the individual wax components.

3. A container for holding liquids formed from a fibrous sheet material and provided with an adherent moisture and liquid resistant coating, said coating being formed from the wax composition of claim 1.

4. A new composition of matter consisting essentially of parafiin waxes, said composition having a melting point of from 130 F. to 132 F., a viscosity at 210 F. of from 38 to 41 SUS, a penetration at 100 F. of from to 80, and a modulus of rupture of from about 420 to 500, the modulus of rupture being at least 30 units higher than the modulus of rupture of the paraffin wax components.

References Cited in the file of this patent UNITED STATES PATENTS 2,467,959 Bowman et a1. Apr. 19, 1949 2,756,180 Perry et a1 July 24, 1956 

1. A WAX COMPOSITION CONSISTING ESENTIALLY OF FROM 70% TO 85% OF A PARAFFIN WAX HAVING A MELTING POINT OF FROM 125*F. TO 132*F., A PENETRATION AT 77*F. OF FROM 17 TO 23, A VISCOSITY AT 210*F. OF FROM 36 TO 39 SUS AND A MODULUS OF RUPTURE AT 73*F. OF FROM ABOUT 270 TO 340, AND FROM 15% TO 30% OF A PARAFFIN WAC HAVING A MELTING POINT OF FROM 148*F. TO 154*F., A PENETRATION AT 100*F. OF FROM 13 TO 19, A VISCOSITY AT 210*F. OF FROM 40 TO 46 SUS, AND A MODULUS OF RUPTURE OF FROM ABOUT 340 TO
 400. 